This novel device in operational mode A is a two stage enhanced evaporative cooler which can be transformed into a heater by changing to operational mode B. It can be used in open or closed loop configuration for controlling the temperature of one or more ambients.
Evaporative coolers in use today, achieve a temperature reduction of the circulating air by a water surface evaporation process, this is an isoenthalpic process where the air temperature is lowered by heat transfer to the evaporating water. Consequently the air's moisture is increased up to the dew point. Such final state may not be comfortable when the initial air temperature and relative moisture are only a few degrees from dew point. This characteristic limits the application of this type of cooling to very dry weather conditions.
Various systems have been patented to solve such shortcomings: U.S. Pat. No. 5,050,391 refers to a double sided heat exchanger having a dry surface along which the air flows. The opposite side is cooled by water evaporation. This general method of cooling one surface of one element by water evaporation while cooling the usable air with the dry opposite side of the same element or another element thermally connected are the basis for U.S. Pat. Nos. 4,002,040 and 5,453,223
U.S. Pat Nos. 4,171,620; 4,786,301; 4,864,830; 4,982,575 and 5,460,004 all in different ways make use of desiccants to reduce the relative humidity of the cooled air.
In the present invention no desiccants are required and the porous element and or double sided opposite surfaces elements are substituted by an array or plurality of finned evaporation channels plus a second stage which is a conventional air to water heat exchanger. This combination produces a cool, dry air which is desirable for comfort.
On application P19980103167 "Acondicionador de Aire Por Evaporacion y Calefactor," of this same author at the Patent Office in Buenos Aires, Argentina, the water drained from the first stage, evaporation tubes, is mixed with the water drained from the second stage, heat exchanger, in a common single tray and pumped by a single pump to both stages. This method resulted inefficient by requiring a long time to lower the water temperature in the single tray to the best operational value.
In the present invention such inconvenience is overcome by the use of two separate water trays, one for cold water, one for warm water, each one with an independent pump, such that in the cooler mode the warm water drained from the heat exchanger is directly pumped to the evaporation channels where it is cooled then pumped to the heat exchanger where it will absorb the heat from the air and will be drained to the warm water tray, in a continuous cycle.
By having a separate tray and pump for the cold water, a lower operating temperature is achieved in a shorter time. This arrangement, allows for the use of more than one heat exchanger which can be in a remote location.
Basically this novel system works with a fundamentally different thermal cycle than the one in previous patents. An additional difference is that the fins of the evaporation channels provides for a pre-cooling of the air in its way to the second stage. Also the method of indirect spraying by impacting of a high pressure water jet to produce a very fine spray, allows for larger diameter nozzles, avoiding the clogging so frequent in systems with direct spraying requiring very small diameter ejection holes.